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BASS. XXXV. The M BH–σ Relation of 105 Month Swift-BAT Type 1 AGNs
Abstract We present two independent measurements of stellar velocity dispersions ( σ ⋆ ) from the Ca ii H+K λ 3969, 3934 and Mg i b λ 5183, 5172, 5167 region (3880–5550 Å) and the calcium triplet region (8350–8750 Å) for 173 hard X-ray-selected Type 1 active galactic nuclei (AGNs; z ≤ 0.08) from the...
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Published in: | The Astrophysical journal 2023-10, Vol.956 (1), p.60 |
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Main Authors: | , , , , , , , , , , , , , , , , , , , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | Abstract
We present two independent measurements of stellar velocity dispersions (
σ
⋆
) from the Ca
ii
H+K
λ
3969, 3934 and Mg
i
b
λ
5183, 5172, 5167 region (3880–5550 Å) and the calcium triplet region (8350–8750 Å) for 173 hard X-ray-selected Type 1 active galactic nuclei (AGNs;
z
≤ 0.08) from the 105 month Swift-BAT catalog. We construct one of the largest samples of local Type 1 AGNs that have both single-epoch
virial
black hole mass (
M
BH
) estimates and
σ
⋆
measurements obtained from high spectral resolution data, allowing us to test the usage of such methods for supermassive black hole studies. We find that the two independent
σ
⋆
measurements are highly consistent with each other, with an average offset of only 0.002 ± 0.001 dex. Comparing
M
BH
estimates based on broad emission lines and stellar velocity dispersion measurements, we find that the former is systematically lower by ≈0.12 dex. Consequently, Eddington ratios estimated through broad-line
M
BH
determinations are similarly biased (but in the opposite way). We argue that the discrepancy is driven by extinction in the broad-line region. We also find an anticorrelation between the offset from the
M
BH
–
σ
⋆
relation and the Eddington ratio. Our sample of Type 1 AGNs shows a shallower
M
BH
–
σ
⋆
relation (with a power-law exponent of ≈3.5) compared with that of inactive galaxies (with a power-law exponent of ≈4.5), confirming earlier results obtained from smaller samples. |
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ISSN: | 0004-637X 1538-4357 |
DOI: | 10.3847/1538-4357/acf11b |